Method of forming a low-K dielectric film

ABSTRACT

Methods of forming a semiconductor device are provided. The methods include, for example, forming a low-k dielectric having a continuous planar surface, and, after forming the low-k dielectric, subjecting the continuous planar surface of the low-k dielectric to an ethylene plasma enhanced chemical vapor deposition (PECVD) treatment.

FIELD OF THE INVENTION

The present invention generally relates to methods of formingsemiconductor devices, and more particularly, to methods of formingsemiconductor devices having low-k dielectric films.

BACKGROUND OF THE INVENTION

Low-k dielectrics are those having a smaller dielectric constant (whichrepresents the ratio of the permittivity of a material divided bypermittivity of vacuum) relative to silicon dioxide (SiO₂), which has adielectric constant of 3.9. They can be useful as, e.g. intermetaldielectrics, IMDs, and as interlayer dielectrics, ILDs

In digital circuits, dielectrics separate conducting components (e.g.,wire interconnects and transistors) from one another. As the size ofcircuit elements becomes smaller, semiconductor components have scaled,and so have dielectrics. With scaling, resistance capacitance (RC) delaytime has increasingly dominated circuit performance. In somecircumstances, dielectrics have thinned to the point where, e.g., chargebuild up and crosstalk adversely affect the performance of semiconductordevices. By replacing traditional dielectrics such as silicon dioxidewith low-k dielectrics, RC delay/parasitic capacitance can be reduced,thereby enabling faster switching speeds and lower heat dissipation.Thus, in the semiconductor fabrication industry, there has been aninterest in incorporating low-k dielectric materials into semiconductorsas a strategy to allow for continued scaling of microelectronic devices.

However, low-k dielectrics can present problems during downstreamprocessing. For example, integrating low-k dielectrics successfully intoa reliable CMOS device manufacturing process proves to be extremelydifficult due to the dielectric film having low resistance to thedownstream process-induced damage (including, e.g., polishing, wetprocesses, ashing, etching, and preclean plasma damage during, e.g.,copper diffusion barrier deposition).

Thus, a need exists for improved methods of forming semiconductordevices incorporating low-k dielectric films that can better withstanddownstream processing.

While certain aspects of conventional technologies have been discussedto facilitate disclosure of the invention, Applicants in no way disclaimthese technical aspects, and it is contemplated that the claimedinvention may encompass one or more of the conventional technicalaspects discussed herein.

In this specification, where a document, act or item of knowledge isreferred to or discussed, this reference or discussion is not anadmission that the document, act or item of knowledge or any combinationthereof was, at the priority date, publicly available, known to thepublic, part of common general knowledge, or otherwise constitutes priorart under the applicable statutory provisions; or is known to berelevant to an attempt to solve any problem with which thisspecification is concerned.

SUMMARY OF THE INVENTION

Briefly, the present invention satisfies the need for improved methodsof forming semiconductor devices incorporating low-k dielectric filmsthat can better withstand downstream processing. It has been found thatdownstream processing increases the effective dielectric constant.Embodiments of the invention counter the effects of downstreamprocessing by, for example, providing a low-k dielectric with a reduceddielectric constant, and by providing semiconductor devicesincorporating the improved low-k dielectric.

The present invention may address one or more of the problems anddeficiencies of the art discussed above. However, it is contemplatedthat the invention may prove useful in addressing other problems anddeficiencies in a number of technical areas. Therefore, the claimedinvention should not necessarily be construed as limited to addressingany of the particular problems or deficiencies discussed herein.

Certain embodiments of the presently-disclosed methods of forming asemiconductor device have several features, no single one of which issolely responsible for their desirable attributes. Without limiting thescope of these methods as defined by the claims that follow, their moreprominent features will now be discussed briefly. After considering thisdiscussion, and particularly after reading the section of thisspecification entitled “Detailed Description of the Invention,” one willunderstand how the features of the various embodiments disclosed hereinprovide a number of advantages over the current state of the art. Theseadvantages may include, without limitation, providing improved methodsof forming semiconductor devices by, for example, incorporating improvedlow-k dielectrics having reduced dielectric constants.

These and other features and advantages of this invention will becomeapparent from the following detailed description of the various aspectsof the invention taken in conjunction with the appended claims and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart displaying the linear relationship between dielectricconstant (k) and ethylene PECVD treatment time.

FIG. 2 is a column chart displaying the dielectric constant (k) forExamples 1, 5, and 6.

FIGS. 3-5 are charts depicting Fourier Transform Infrared Spectroscopy(FTIR) traces comparisons for Examples 10-12.

FIG. 6 is a chart depicting a Fourier Transform Infrared Spectroscopy(FTIR) traces comparison for Examples 13-15.

FIG. 7 is a flow chart depicting the steps of an embodiment of theinventive method.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is generally directed to methods of formingsemiconductor devices, and more particularly, to methods of formingsemiconductor devices having a low-k dielectric.

Although this invention is susceptible to embodiment in many differentforms, certain embodiments of the invention are shown and described. Itshould be understood, however, that the present disclosure is to beconsidered as an exemplification of the principles of this invention andis not intended to limit the invention to the embodiments illustrated.

In one aspect, the invention provides a method of forming asemiconductor device. The method includes: forming a low-k dielectrichaving a continuous planar surface where the formed low-k dielectric hasa dielectric constant k_(a); and, after forming the low-k dielectric,subjecting the continuous planar surface of the low-k dielectric to anethylene plasma enhanced chemical vapor deposition (PECVD) treatment.

In various embodiments, the forming a low-k dielectric step is performedduring a process for forming electrical interconnect structures for asemiconductor device, as described, for example, in U.S. Pat. No.7,629,272. The low-k dielectric may be formed (e.g. deposited or coated)on a substrate.

Non-limiting examples of processes that may be used to form the low-kdielectric film include chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), high density PECVD, photon assistedCVD, plasma-photon assisted CVD, cryogenic CVD, chemical assisted vapordeposition, hot-filament CVD, CVD of a liquid polymer precursor,deposition from supercritical fluids, transport polymerization (“TP”),spin coating, dip coating, Langmuir-blodgett self-assembly, and mistingdeposition methods.

The formed low-k dielectric may be any art-acceptable dielectric havinga dielectric constant k_(a) less than or equal to 3.5. For example, insome embodiments, the formed low-k dielectric has a dielectric constantk_(a) of 3.5, 3.4, 3.3, 3.2, 3.1, 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4,2.3, 2.2, 2.1, 2.0, or less, including any and all ranges and subrangestherein.

As used herein, “low-k dielectric” includes ultra low-k dielectrics(those having a dielectric constant less than or equal to about 2.5),and extreme low-k dielectrics (those having a dielectric constant lessthan or equal to about 2.0).

In some embodiments, the low-k dielectric includes a material which is,or has as a precursor, a silicon-containing compound which containssilicon, carbon, oxygen and hydrogen atoms. That is, in theseembodiments, the low-k dielectric contains the silicon-containingcompound, or the low-k dielectric is formed using the silicon-containingcompound as a precursor material.

In some embodiments, the low-k dielectric includes a material which is,or has as a precursor, a material selected from diethoxymethylsilane(for example, commercially available DEMS, from Air Products) andoctamethylcyclotetrasiloxane (for example, commercially available OMCTS,from Air Liquide).

In some embodiments, the low-k dielectric includes a material which is,or has as a precursor, a material selected from: organo silicate glass(OSG), polyarylene ether, hydrogen silesquioxane (HSQ), methylsilsesquioxane (MSQ), polysilsequioxane, polyimide, benzocyclobutene,polytetrafluoroethylene (PTFE), and fluorinated silicate glass (FSG).Additional suitable low-k dielectrics are described, for example, inU.S. Pat. No. 7,135,402.

In some embodiments, the formed low-k dielectric further includes aporogen material.

In some embodiments, the porogen material may include, inter alia, ahydrocarbon material, labile organic group, solvent, decomposablepolymer, surfactant, dendrimer, hyper-branched polymer, orpolyoxyalkylene compound, or any combination thereof.

In embodiments where the low-k dielectric includes a porogen material,the porogen material may be completely or partially removed during oneor more processing steps (e.g., curing) subsequent to the low-kdielectric formation step.

In some embodiments, the method of forming a semiconductor deviceincludes a curing step. In some embodiments, a curing step is performedon the low-k dielectric after forming the low-k dielectric and prior tothe ethylene PECVD treatment. More particularly, in some embodiments, atleast the continuous planar surface of the low-k dielectric is subjectedto a curing treatment. The curing step, where present, may include anyart-accepted curing treatment. For example, in some embodiments, thecuring step may include ultraviolet (UV) curing, vacuum ultlraviolet(VUV) curing, and/or thermal curing.

In particular embodiments, the curing step includes subjecting thecontinuous planar surface of the low-k dielectric to UV curing.

In some embodiments, the curing step may increase the crosslinkingdensity of the low-k dielectric.

In some embodiments, the curing step may be carried out such that atleast a portion of porogen material, where present, is removed from thelow-k dielectric. In embodiments where only a portion of porogenmaterial, where present, is removed, subsequent curing steps mayoptionally be performed during semiconductor processing to removeessentially all remaining porogen material.

In some embodiments, the curing step is carried out such thatessentially all of the porogen material, where present, is removed.

In some embodiments, the removal of porogen material during asemiconductor device manufacturing process step, such as curing, causesthe formation of pores in the low-k dielectric. The pore-including low-kdielectric may also be referred to as a porous low-k dielectric.

After forming the low-k dielectric, and in various embodiments, aterperforming one or more curing steps, the method of the inventionincludes subjecting the continuous planar surface of the low-kdielectric to an ethylene plasma enhanced chemical vapor deposition(PECVD) treatment.

As used herein, “continuous planar surface” refers generally to anuninterrupted flat surface. For purposes of the invention, a low-kdielectric surface may be referred to as a continuous planar surfaceregardless of whether the low-k dielectric is porous or non-porous, andregardless of whether pores are present at the surface. However, whereone or more recessed features have been created in a low-k dielectric(e.g., vias, trenches, etc.), the surface of the low-k dielectric wouldnot be considered to be a continuous planar surface, because the surfacewould, at the least, lack continuity. Recessed features may be causedby, for example, one or more plasma etching processes. Plasma etchingcan also cause, for example, surface roughness on a dielectric, whichwould result in a non-planar surface. Accordingly, while methods of theinvention may include processes to form recessed features in the low-kdielectric, such processes would only be performed after a dielectrichaving a continuous planar surface has been formed, and after thecontinuous planar surface of the low-k dielectric has been treated withan ethylene PECVD treatment.

In some embodiments, the average surface roughness of the formed andoptionally cured low-k dielectric, prior to ethylene PECVD treatment, isless than or equal to 2.50 nm, for example, in some embodiments, 2.50,2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90,1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30,1.25, or 1.20 nm or less, including any and all ranges and subrangestherein (e.g., 1.50 to 2.25 nm).

The ethylene PECVD treatment of the inventive methods yields a treatedlow-k dielectric having a dielectric constant k_(b). In someembodiments, k_(b)<k_(a). In some embodiments, k_(b) is less than orequal to 2.8. For example, in some embodiments, k_(b) is 2.8, 2.7, 2.6,2.5, 2.4, 2.3, 2.2, 2.1, 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, or 1.4, includingany and all ranges and subranges therein (e.g., 1.8 to 2.6). In someembodiments, k_(b) is less than 2.6, for example, less than 2.4.

According to some embodiments of methods of the invention, the percentchange between k_(a) and k_(b)

$\left( {\frac{k_{a} - k_{b}}{k_{a}} \times 100\%} \right)$is at least 5%. For example, according to such embodiments, if k_(a) is3.0, then k_(b) must be less than or equal to 2.85.

In some embodiments, the percent change between k and k is 3% to 30%,e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, or 30%, including all ranges andsubranges therein (e.g., 5-25%).

The thickness of the treated low-k dielectric may be any desiredthickness. In some embodiments, following the ethylene PECVD-treatment,the treated dielectric has an average thickness of 300 to 6,000 Å. Forexample, in some embodiments, the treated low-k dielectric has anaverage thickness of 300, 400, 600, 800, 1,000, 1,200, 1,400, 1,600,1,800, 2,000, 2,200, 2,400, 2,600, 2,800, 3,000, 3,200, 3,400, 3,600,3,800, 4,000, 4,200, 4,400, 4,600, 4,800, 5,000, 5,200, 5,400, 5,600,5,800, or 6,000 Å, including any and all ranges and subranges therein(e.g. 1.000 to 5,000 Å, 1,500 to 4,000 Å, 1,600 to 3,000 Å, etc.)

In some embodiments, the ethylene PECVD treatment according to theinvention utilizes a noble gas, for example, helium. The ethylene PECVDtreatment may use, for example, a reactor pressure of 1 to 10 Torr, forexample, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 Torr, including any and allranges and subranges therein (e.g., 4 to 8 Torr). In some embodiments,the ethylene PECVD treatment is performed at a temperature of 200 to500° C., for example, 200, 250, 300, 350, 400, 450, or 500° C.,including any and all ranges and subranges therein (e.g., 300 to 400°C.). The continuous planar surface of the low-k dielectric is subjectedto the ethylene PECVD treatment for any desired treatment time. Forexample, in some embodiments, the continuous planar surface of the low-kdielectric is subjected to the ethylene PECVD treatment for 10 to 250seconds, for example, for 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110,120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 250seconds, including all ranges and subranges therein (e.g., 15 to 200seconds). The treatment time may be continuous or intermittent.

In some embodiments, the ethylene PECVD treatment results in ethylenepenetrating 50-300 Å into the low-k dielectric (e.g., 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, or 300 Å including any and all rangesand subranges therein (e.g., 100-290 Å). In some embodiments, theethylene PECVD treatment results in ethylene penetrating less than orequal to 300 Å into the low-k dielectric.

In some embodiments, the inventive method includes repeating the forminga low-k dielectric step and the ethylene PECVD treatment step one ormore times (e.g., 1, 2, 3 times, etc.). For example, following a firstethylene PECVD treatment step, one or more additional processing stepsmay be performed. Subsequent to the first forming a low-k dielectricstep and the first ethylene PECVD treatment step, and any desirableadditional process steps, a second forming a low-k dielectric step maybe performed to form a second low-k dielectric, having the same or adifferent composition to the first, and having its own continuous planarsurface. After forming the second low-k dielectric, the continuousplanar surface of the second low-k dielectric may be subjected to asecond ethylene plasma enhanced chemical vapor deposition (PECVD)treatment.

Methods of the invention may include, or be used together with othersemiconductor fabrication processes. For example, following ethylenePECVD treatment, the low-k dielectric may be patterned usingconventional lithographic techniques including, e.g., a hard mask, inthe process flow. The patterned low-k dielectric material may be coatedwith, e.g., a barrier/copper seed layer generally employed forsubsequent deposition of a copper interconnect structure in thevias/trenches provided by the patterned low-k dielectric layer. Thesubstrate may then be subjected to a chemical mechanical polish processfor planarizing the patterened copper surface, followed by anyadditional desirable processing.

EXAMPLES

The invention will now be illustrated, but not limited, by reference tothe specific embodiments described in the following examples.

Examples 1-6

For Examples 1-6, low-k dielectric films were deposited using acommercial 300 mm Plasma Enhanced Chemical Vapor Deposition (PECVD)system by simultaneously admixing a precursor containing C, H, Si, O anda hydrocarbon porogen precursor in the chamber and application of 13.56MHz RF power. Subsequent exposure to UV irradiation in a 300 mm systemfor 160 seconds at 385° C. resulted in the removal of porogen (CHxphase) to create porosity in the film and therefore a lower k. UV curingalso enhanced the mechanical properties due to cross linking of theSiCOH skeleton.

Following low-k dielectric formation and curing, ethylene PECVDtreatment was performed on Examples 2-6 for 30-120 seconds using acommercial 300 mm Plasma Enhanced Chemical Vapor Deposition (PECVD)system by a C2H4 plasma diluted with noble gas(es) (He) activated with13.56 MHz RF power. Ethylene PECVD treatment was performed at 350° C.,6.2 Torr.

The resultant film properties for Examples 1-6 are presented below inTable L For each example, the dielectric constant (k) value was measuredby Capacitance-voltage (C-V) measurements of EOT by KLA-Tencor Quantoxtool. The dielectric constant of each film was calculated by combiningEOT with physical thickness, using the equation; PhysicalThickness=EOT*(dielectric constant/3.9).

TABLE I Ethylene Thickness Non- UV Cure PECVD Avg. Dielectrc UniformityReflective Quantox k by Ex. Deposition Conditions Treatment Thickness, Å(49points data) Index EOT, Å Quantox 1 Low-k dieletric 385° C., 0 sec1530.16 1.01 1.3787 2181 2.736 (DEMS as precursor) 160 sec 2 Low-kdieletric 385° C., 30 sec 1769.97 1.28 1.4263 2685 2,570 (DEMS asprecursor) 160 sec 3 Low-k dieletric 385° C., 60 sec 1909.34 1.16 1.48952995 2.486 (DEMS as precursor) 160 sec 4 Low-k dieletric 385° C., 60 sec1919.19 1.10 1.4887 3011 2.485 (DEMS as precursor) 160 sec 5 Low-kdieletric 385° C., 120 sec 1996.40 0.56 1.6628 3669 2.122 (DEMS asprecursor) 160 sec 6 Low-k dieletric 385° C., 120 sec 2000.81 0.791.6631 3666 2.128 (DEMS as precursor) 160 sec

As shown above, where Example 1 represents the control, ethylene PECVDtreatment reduced the dielectric constant for each of Examples 2-6according to the invention, thereby making the treated low-k dielectricsmore conducive to, and desirable for during downstream processing.

FIG. 1 is a chart displaying the linear relationship between dielectricconstant (k) and ethylene PECVD treatment time, where dielectricconstants were measured using Quantox, as in Table I above. Asillustrated, dielectric constant values decreased as a function ofexposure time to ethylene PECVD treatment.

FIG. 2 is a column chart displaying the dielectric constant (k) forExamples 1, 5, and 6, with k confirmed with metal-insulator-metal (MIM)structure using metal dots. As shown, Examples 5 and 6 according to theinvention effectively lowered the dielectric constant from about 2.7 toabout 2.3.

Examples 7-9

Examples 7-9 were prepared according to the protocol set forth above forexamples 1-6, except that the UV-curing step was omitted, and thedielectric constant of each film was measured by C-V withmetal-insulator-metal structure.

The resultant film properties for examples 7-9 are presented below inTable II.

TABLE II Ethylene Thickness k, measured by C-V with PECVD Avg.Dielectric Non-Uniformity Reflective metal-insulator-metal Ex.Deposition Treatment Thickness, Å (49points data) Index structure 7Dense low-k dieletric  0 sec 2806 1.87 1.4026 2.736 (OMCTS as precursor)8 Dense low-k dieletric 30 sec 2931 1.65 1.4337 2.570 (OMCTS asprecursor) 9 Dense low-k dieletric 60 sec 3063 1.39 1.4811 2.486 (OMCTSas precursor)

As shown, methods of the invention effectively reduce dielectricconstant regardless of whether the formed low-k dielectric is curedbefore ethylene PECVD treatment.

Examples 10-12 Repairing O2 Plasma Damage

Examples 10-12 were prepared according to the protocol set forth abovefor examples 1-6, using DEMS as a low-k dielectric precursor.

Of Examples 10-12, Example 10 represents the control, which was notsubjected to further treatment following low-k dielectric formation andcuring.

Following low-k dielectric formation and curing, Examples 11 and 12 weresubjected to oxygen (O₂) plasma damage for 18 seconds using a commercial300 mm Plasma Enhanced Chemical Vapor Deposition (PECVD) system by a O2plasma diluted with noble gas(es) activated with 13.56 MHz RF power.Example 12, according to the present invention, was subsequentlysubjected to 30 seconds of ethylene PECVD) treatment, as described abovefor Example 2.

FIGS. 3-5 are charts depicting Fourier Transform infrared Spectroscopy(FTIR) traces comparisons for Examples 10-12, plotted on common scaleand normalized to 1 μm thickness. As shown, recoveries for bothAlkyl-CH2 and Si—CH3 bonding resulted when the sample of Example 11 wastreated with ethylene PECVD treatment according to the present inventionto yield Example 12. Thus, exposure to ethylene PECVD treatmentfavorably restores CHx bondings.

Examples 13-15 Repairing CO2/CO Plasma Damage

Examples 13-15 were prepared according to the protocol set forth abovefor examples 1-6, using DEMS as a low-k dielectric precursor.

Of Examples 13-15, Example 13 represents the control, which was notsubjected to further treatment following low-k dielectric formation andcuring.

Following low-k dielectric formation and curing, Examples 14 and 15 weresubjected to CO₂/CO plasma damage for 20 seconds using a using acommercial 300 mm Reactive Ion Etch (RIE) system by a CO2/CO plasmadiluted with noble gas(es). Example 15, an example according to thepresent invention, was subsequently subjected to 30 seconds of ethylenePECVD treatment, as described above for Example 2.

FIG. 6 is a chart depicting a Fourier Transform Infrared Spectroscopy(FTIR) traces comparison for Examples 13-15, plotted on common scale andnormalized to 1 μm thickness. As depicted, exposure to ethylene PECVDtreatment favorably restores CHx bondings.

FIG. 7 is a flow chart depicting the steps of an embodiment of theinventive method, including formation step 10 for forming a low-kdielectric having a continuous planar surface, the low-k dielectrichaving a dielectric constant k_(a), followed by optional curing step 20,and subsequently ethylene PECVD treatment step 30, for subjecting thecontinuous planar surface of the low-k dielectric to an ethylene PECVDtreatment, which may be followed by further semiconductor fabricationprocess step(s) 40. Certain embodiments of these inventive methodsintegrate a low-k dielectric having a reduced dielectric constant intothe back end of line of CMOS, thereby allowing for RC delay to besignificantly reduced following downstream processing. Some embodimentsthus also provide for improved chip performance and reduced chipmanufacturing costs.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has” and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises”, “has”,“includes” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises”, “has”, “includes” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

As used herein, the terms “comprising” and “including” or grammaticalvariants thereof are to be taken as specifying the stated features,integers, steps or components but do not preclude the addition of one ormore additional features, integers, steps, components or groups thereof.This term encompasses the terms “consisting of” and “consistingessentially of”.

The phrase “consisting essentially of” or grammatical variants thereofwhen used herein are to be taken as specifying the stated features,integers, steps or components but do not preclude the addition of one ormore additional features, integers, steps, components or groups thereofbut only if the additional features, integers, steps, components orgroups thereof do not materially alter the basic and novelcharacteristics of the claimed composition, device or method.

Where one or more ranges are referred to throughout this specification,each range is intended to be a shorthand format for presentinginformation, where the range is understood to encompass each discretepoint within the range as if the same were fully set forth herein.

While several aspects and embodiments of the present invention have beendescribed and depicted herein, alternative aspects and embodiments maybe affected by those skilled in the art to accomplish the sameobjectives. Accordingly this disclosure and the appended claims areintended to cover all such further and alternative aspects andembodiments as fall within the true spirit and scope of the invention.

The invention claimed is:
 1. A method of forming a semiconductor device,said method comprising: forming a low-k dielectric having a continuousplanar surface, the low-k dielectric having a dielectric constant k_(a);and after forming the low-k dielectric, subjecting the continuous planarsurface of the low-k dielectric to an ethylene plasma enhanced chemicalvapor deposition (PECVD) treatment.
 2. The method according to claim 1,wherein the low-k dielectric comprises a material which is, or has as aprecursor, a silicon-containing compound comprising silicon, carbon,oxygen and hydrogen atoms.
 3. The method according to claim 2, whereinthe low-k dielectric comprises a material which is, or has as aprecursor, a material selected from diethoxymethylsilane andoctamethylcyclotetrasiloxane.
 4. The method according to claim 1,wherein the low-k dielectric comprises a material which is, or has as aprecursor, a material selected from: organo silicate glass (OSG),borophosphosilicate glass (BPSG), borosilicate glass (BSG),phosphosilicate glass (PSG), polyarylene ether, hydrogen silesquioxane(HSQ), methyl silsesquioxane (MSQ), polysilsequioxane, polyimide,benzocyclobutene, polytetrafluoroethylene (PTFE), and fluorinatedsilicate glass (FSG).
 5. The method according to claim 2, wherein thelow-k dielectric further comprises a porogen material.
 6. The methodaccording to claim 5, wherein the porogen material comprises ahydrocarbon material, labile organic group, solvent, decomposablepolymer, surfactant, dendrimer, hyper-branched polymer, orpolyoxyalkylene compound, or any combination thereof.
 7. The methodaccording to claim 1, wherein, after forming the low-k dielectric andprior to the ethylene PECVD treatment, a curing step is performed on thelow-k dielectric.
 8. The method according to claim 7, wherein the curingstep comprises subjecting the continuous planar surface of the low-kdielectric to ultraviolet (UV) curing.
 9. The method according to claim2, wherein the ethylene PECVD treatment yields a treated low-kdielectric having a dielectric constant k_(b), where k_(b)<k_(a). 10.The method according to claim 9, wherein the percent change betweenk_(a) and k_(b)$\left( {\frac{k_{a} - k_{b}}{k_{a}} \times 100\%} \right)$ is at least5%.
 11. The method according to claim 9, wherein k_(a) is less than 3.12. The method according to claim 9, wherein k_(b) is less than 2.6. 13.The method according to claim 12, wherein k_(b) is less than 2.4. 14.The method according to claim 9, wherein the ethylene PECVD treatment isperformed at a pressure of 4 to 8 Torr.
 15. The method according toclaim 9, wherein the ethylene PECVD treatment is performed at atemperature of 300 to 400° C.
 16. The method according to claim 9,wherein the continuous planar surface of the low-k dielectric issubjected to the ethylene PECVD treatment for 15 to 200 seconds.
 17. Themethod according to claim 9, wherein the low-k dielectric comprises amaterial which is, or has as a precursor, a material selected fromdiethoxymethylsilane and octamethylcyclotetrasiloxane.
 18. The methodaccording to claim 9, wherein, after forming the low-k dielectric andprior to the ethylene PECVD treatment, a curing step is performed on thelow-k dielectric.
 19. The method according to claim 18, wherein thecuring step comprises subjecting the continuous planar surface of thelow-k dielectric to ultraviolet (UV) curing.
 20. The method according toclaim 2, said method comprising repeating the forming a low-k dielectricstep and the ethylene PECVD treatment step one or more times.